{
  "resourceType": "StructureDefinition",
  "id": "questionnaire-unitOption",
  "extension": [
    {
      "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-wg",
      "valueCode": "fhir"
    },
    {
      "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm",
      "valueInteger": 1
    }
  ],
  "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-unitOption",
  "version": "4.6.0",
  "name": "unitOption",
  "status": "draft",
  "date": "2013-07-04",
  "publisher": "HL7",
  "contact": [
    {
      "telecom": [
        {
          "system": "url",
          "value": "http://www.hl7.org"
        }
      ]
    }
  ],
  "description": "A unit that the user may choose when providing a quantity value.",
  "fhirVersion": "4.6.0",
  "mapping": [
    {
      "identity": "rim",
      "uri": "http://hl7.org/v3",
      "name": "RIM Mapping"
    }
  ],
  "kind": "complex-type",
  "abstract": false,
  "context": [
    {
      "type": "element",
      "expression": "Questionnaire.item"
    }
  ],
  "contextInvariant": [
    "type='quantity'"
  ],
  "type": "Extension",
  "baseDefinition": "http://hl7.org/fhir/StructureDefinition/Extension",
  "derivation": "constraint",
  "differential": {
    "element": [
      {
        "id": "Extension",
        "path": "Extension",
        "short": "Unit choice",
        "definition": "A unit that the user may choose when providing a quantity value.",
        "comment": "Provide either unitOption(s) or unitValueSet.  If either of the extensions are present, the units for a Quantity element are constrained to only the units listed by the extensions - i.e. it is treated as a \"required\", not an \"extensible\" binding.  In the absence of either, any unit is valid.  See additional guidance and examples in the [SDC implementation guide](http://build.fhir.org/ig/HL7/sdc/behavior.html#unitOption).",
        "min": 0,
        "max": "*",
        "mapping": [
          {
            "identity": "rim",
            "map": "N/A (MIF-level)"
          }
        ]
      },
      {
        "id": "Extension.extension",
        "path": "Extension.extension",
        "max": "0"
      },
      {
        "id": "Extension.url",
        "path": "Extension.url",
        "fixedUri": "http://hl7.org/fhir/StructureDefinition/questionnaire-unitOption"
      },
      {
        "id": "Extension.value[x]",
        "path": "Extension.value[x]",
        "min": 1,
        "type": [
          {
            "code": "Coding"
          }
        ]
      }
    ]
  }
}